The Line Jack Unit has two primary parts.
1. Female connector unit called the Line Jack Unit socket.
2. Telephone cord connector with RJ-11 plug.

Primary Line Jack Unit

The unit compromise of printed circuit board on which electronic components are mounted.
a) Capacitor
b) Resistor
c) Surge voltage protection device
d) Screw in type terminal block.
e) Socket outlet enabling the unit to be connected to a telephone or other equipment.

The circuit board is mounted to a high grade plastic front cover assembly which contains a shutter assembly to prevent in grass of dust and insects.
To complete the assembly, a back box is provided enabling the unit to be mounted on a wall or other suitable fixtures.

Secondary Line Jack Unit

The unit is physically is same as Primary Line Jack Unit but contains no electronic components.

It is used in conjunction with a Primary Line jack Unit as an extension to the same line and because it is wired in a parallel, the component in the Primary Line Jack Unit acts in the same way in subsequent Secondary Line Jack Unit thus enabling equipment to operate in any Secondary Line Jack Unit with or without equipment connected to the Primary Line Jack Unit.